Donald Trump believes he is on track to make a swift comeback after spending weeks trailing Hillary Clinton in a series of national and battleground state polls.

"If you look at the most recent polls I think things are turning," Trump said Monday during an interview on Fox News. "I think they're turning rather rapidly."

The Republican presidential nominee continued to push back on Clinton over the possible pay-to-play practices her charitable foundation engaged in during her tenure as secretary of state, saying "it's hard to believe she can be running."

"Look, these are very greedy people. These are people that have skirted the law for a long time. Hard to believe that, you know, somebody like this has a good chance, you know — a fairly good chance of being president," Trump said.

"To be honest with you, with the emails and the crime she committed, she shouldn't even be allowed to run for president," he added.

Trump frequently touted his standing in the polls during the GOP primary and early in the general election when he was within striking distance of Clinton. He has avoided giving a rundown of recent polls during his campaign rallies since the Democratic convention concluded last month.